Magnetic tapes are known as portable record media which have large storage capacity and the costs per storage capacity of which are low. Magnetic tapes are widely used as, for example, backup record media.
A method for backing up data on a main data magnetic tape and backing up on an auxiliary data magnetic tape data which is the same as that saved on the main data magnetic tape is known as one of backup methods using a magnetic tape. By adopting this method, data can be recovered by the use of the auxiliary data magnetic tape even if an abnormality occurs in the main data magnetic tape at the time of data recovery. This reduces the risk of losing backup data. Furthermore, a main data magnetic tape associated with a backup source storage area is used at backup time. As a result, a main data magnetic tape, which is a backup destination, corresponding to a storage area can be managed easily.
In order to back up data on a main data magnetic tape and an auxiliary data magnetic tape, the following techniques are proposed. For example, a technique for recording data outputted from a host apparatus on a magnetic tape at once in parallel is proposed. With this technique, an operation is simplified and time taken to perform backup is reduced.
In addition, another technique is proposed. Data and instructions to write the data are received from a host server. The data is written to a disk array and is written from the disk array to a tape. If the tape or the contents of the data meet a determined condition, then the data is also written to a spare tape. By doing so, data integrity is enhanced by the use of a small number of tapes.
Japanese Laid-open Patent Publication No. 2001-209501
Japanese Laid-open Patent Publication No. 2011-108091
By the way, there are cases where data in storage areas (disk volumes, logical volumes, or the like) is backed up on different magnetic tapes according to storage areas. This makes it easy to manage the backup destination magnetic tapes corresponding to the storage areas.
If data in each storage area is backed up not only on a main data magnetic tape but also on an auxiliary data magnetic tape and the main data magnetic tape and the auxiliary data magnetic tape are associated with each other on a one-to-one basis, the number of magnetic tapes used for backup increases.